West Wind Drift

West Wind Drift
NASA · Public domain · source
Name	West Wind Drift
Other names	Antarctic Circumpolar Current
Type	Ocean current
Location	Southern Ocean
Length	Circumpolar
Direction	Eastward
Status	Persistent

West Wind Drift

The West Wind Drift is the eastward-flowing circumpolar current encircling Antarctica that connects the Atlantic, Pacific, and Indian Oceans and influences the climates of Antarctica, South America, Africa, Australia, and New Zealand. It plays a central role in the Antarctic thermohaline system, the global Meridional overturning circulation, and in the distribution of marine biota such as krill and penguins. Observations from expeditions including those of James Cook, modern research programs like the International Geophysical Year and institutions such as the Scripps Institution of Oceanography have shaped understanding of its dynamics.

Overview and Nomenclature

The feature commonly called the West Wind Drift is also known as the Antarctic Circumpolar Current and appears in literature from Benjamin Franklin’s time to contemporary work at Woods Hole Oceanographic Institution. Early naming reflects winds observed during voyages by James Cook and later charting by James Clark Ross. Oceanographers at the National Oceanic and Atmospheric Administration and researchers working with the Intergovernmental Panel on Climate Change use the Antarctic Circumpolar Current designation in modern climate assessments and in modeling studies by groups at Princeton University and the National Center for Atmospheric Research.

Physical Oceanography and Dynamics

The current’s dynamics are governed by interactions among the Southern Ocean wind field, the Antarctic Circumpolar Wave, baroclinic instability, and topographically steered jets around features such as the Drake Passage and the Kerguelen Plateau. Momentum input from the Southern Hemisphere westerlies drives a zonal transport that is modulated by mesoscale eddies observed by arrays deployed by teams from Lamont–Doherty Earth Observatory and the Commonwealth Scientific and Industrial Research Organisation. Thermohaline gradients involving Antarctic Bottom Water and Subantarctic Mode Water are central to its stratification, documented using instruments developed at Scripps Institution of Oceanography and the British Antarctic Survey.

Geographic Extent and Pathways

Circulating continuously around Antarctica, the current flows eastward through major choke points including the Drake Passage between South America and Antarctica, the Falkland Islands vicinity, past the South Shetland Islands, around the Kerguelen Plateau and the Crozet Islands, and eastward toward the Tasman Sea and south of New Zealand. It links the southern reaches of the Atlantic Ocean, Indian Ocean, and Pacific Ocean, forming distinct fronts such as the Subantarctic Front and the Polar Front, identified in hydrographic surveys by expeditions like those organized by the Challenger Expedition and later by the German Meteor cruises.

Climatic and Ecological Impacts

By mediating heat and carbon exchange between the Southern Ocean and the global ocean, the current affects regional climates of Patagonia, southern Africa, southeastern Australia, and the Antarctic Peninsula. It influences upwelling that sustains high productivity zones supporting species such as Antarctic krill, Adélie penguin, emperor penguin, albatross species, and squid harvested by fleets from Japan, Spain, and South Korea. Changes in the current have been linked in studies by the Royal Society and the Intergovernmental Panel on Climate Change to shifts in the Southern Annular Mode and to patterns observed during events like the El Niño–Southern Oscillation and the Indian Ocean Dipole that modulate marine ecosystems and fisheries around the Southern Hemisphere.

Role in Global Ocean Circulation

The West Wind Drift forms the only ocean current that completely circumnavigates the globe and serves as a conduit in the global Meridional overturning circulation by facilitating the formation and export of Antarctic Bottom Water and Circumpolar Deep Water. Its transport, measured in Sverdrups by scientists at Scripps Institution of Oceanography and Woods Hole Oceanographic Institution, links to heat and carbon sequestration processes central to projections by the Intergovernmental Panel on Climate Change and to paleoclimate interpretations from cores studied at the British Antarctic Survey and the Alfred Wegener Institute.

Historical Observations and Exploration

Knowledge of the current grew from practical seafaring reports during voyages by James Cook and the sealing and whaling expeditions of the 19th century to systematic hydrographic work by the Challenger Expedition and later scientific cruises such as Meteor. Instrumental advances—reversing thermometers, Nansen bottles, expendable bathythermographs, and modern autonomous floats deployed by the Argo program—have refined maps of velocity, temperature, and salinity, with major contributions from institutions including the Scott Polar Research Institute and the Australian Antarctic Division.

Human Interactions and Economic Significance

The current shapes shipping routes near the Drake Passage and affects safety and timing for voyages to Antarctica and subantarctic islands used by penguin researchers and by Antarctic operators like national programs from Chile, Argentina, Australia, and New Zealand. It influences fisheries targeting Patagonian toothfish and krill, regulated by bodies such as the Commission for the Conservation of Antarctic Marine Living Resources and contested in negotiations involving fleets from Russia, China, and European Union states. Research into renewable energy, carbon sequestration, and climate mitigation by centers at Massachusetts Institute of Technology and Imperial College London considers the current’s role in global heat and carbon budgets.

Category:Ocean currents Category:Southern Ocean Category:Antarctic region